1. Field of the Invention
The present invention relates to a wireless communication method which is suitable for constructing a local area network (LAN) among a plurality of equipments, where various information is transmitted by e.g. a wireless signal, as well as a wireless communicating apparatus and a wireless communication control apparatus to which the wireless communication method is applied.
2. Description of the Related Art
When a local area network is constructed within a comparatively narrow area such as a household, an office or the like so that, among the plurality of equipments such as various video equipments, personal computers, its circumferential devices, and so on transmission of data which is handled by those equipments can be performed, a wireless transmitting/receiving apparatus may be connected to each of these equipments for allowing the data transmission to be performed by wireless instead of making direct connection among those equipments by some signal lines.
Constructing the local area network by wireless transmission enables a system configuration to be simple without any need to directly connect each equipment by signal lines and the like.
Incidentally, when three or more wireless transmitting receiving apparatus (communicating apparatus) are provided to construct the local area network, the CSMA (Carrier Sense Multiple Access) method or the polling method has heretofore been employed in general as an access method.
In case of the CSMA method, transmitting data containing a sender""s address and a receiver""s address is processed to be transmitted to all other communicating apparatus within that network. On a receiving side, if received data is decided to be those addressed to one""s own station from judging the receiver""s address contained in transmitted data, the data is processed to be acquired. In case of the polling method, a control station for controlling the communication is provided and the control station inquires from each communicating apparatus if any transmitting data is present. If the transmitting data is present, the control station gives a transmitting right to a corresponding communicating apparatus allowing it to perform the communication.
In any conventional communication method, the communicating apparatus side which intends to transmit data may transmit without knowing whether or not a receiving side can receive a wirelessly transmitted data and if the receiving side is unable to receive, wireless resources will be wasted. Moreover, a problem has been raised in which each communicating apparatus cannot estimate the quality of a communication with a communicating companion and so it cannot determine in what conditions data should be transmitted.
Accordingly, when the local area network was constructed for making the wireless transmission in the past, the companions with whom each wireless communicating apparatus can communicate were limited to those located within such a near distance that data can securely be transmitted wirelessly. Thus, in case of the system by wireless, it was possible to construct the local area network within very narrow area only.
Particularly, in recent years, data to be wirelessly transmitted through such a local area network involves many data which require a very large transmitting capacity (e.g. several Mbps to dozens Mbps or so ) such as video signal made into digital data, various program data for computer and the like. In order to ensure the transmitting capacity which is enough to process such data, it is necessary to utilize a very high transmitting band (e.g. about 5 GHz). On the other hand, the wireless communicating apparatus for constructing the local area network is limited in its transmitting output and so in case of the apparatus which can be installed without permission, a wirelessly transmissible distance will become a very short distance (e.g. from several meters to dozens meters or so), so that if a distance between the wireless communicating apparatus exceeds the distance allowing the wireless transmission, the receiving side cannot process to receive data correctly.
In view of the foregoing points, an object of the present invention is to ensure the wireless transmission among respective communicating apparatuses when constructing the local area network with a plurality of wireless communicating apparatuses.
According to an aspect of the present invention, there is provided a wireless communication method, in which a wireless signal having a frame structure is transmitted by wireless communication under the control of a control station, the frame structure of the wireless signal includes a managing region and a data transmitting region. In the managing region, transmitted are a test signal for checking the quality of communication among a plurality of communicating stations and communication quality information representative of the quality of communication among the plurality of communicating stations. In the data transmitting field, isochronous data or asychronous data is transmitted under the access control of the control station.
According to the wireless communication method of the present invention, each communicating station can know the quality of communication with other communicating station within the system by receiving the test signal, the communication quality information among the respective communicating stations is produced on the basis of the quality of information, and then the quality information is transmitted to each communicating station, so that each communicating station can estimate conditions of communication within the system.
There is provided a wireless communicating apparatus according to another aspect of the present invention, which comprises a controller unit for controlling the communication in a frame cycle established by a control apparatus for making the access control and a communication processor unit for transmitting or receiving, under the control of the controller, in the managing region established in a first timing section within the frame cycle, the test signal for checking the quality of communication with other wireless communicating apparatus and a test result based on the test signal.
According to the wireless communicating apparatus of the present invention, the wireless communication with other wireless communicating apparatuses is made in the frame cycle and, in the managing region within the frame cycle, the quality of communication with other wireless communicating apparatuses can be checked based on the test signal. The checked test result can also be transmitted to the control apparatus and the like.
Moreover, the wireless communication control apparatus according to the present invention comprises a controller unit for making communication among a plurality of wireless communicating apparatuses to be performed in a frame cycle, establishing a managing field in a region timing section within the frame cycle and establishing a data transmitting region in a second timing, a receiver unit for receiving in the managing region, information which is transmitted from each of the wireless communicating apparatuses and is representative of a test result of conditions of communication with other wireless communicating apparatuses, and a transmitter unit for producing communication quality information from a result of decision by the controller unit deciding the received information representative of the test result and transmitting the produced communication quality information on the managing region.
According to a further aspect of the present invention, there is provided a wireless communication control apparatus. In the managing region within the frame cycle, the communication quality information representative of conditions of communication among the wireless communication apparatuses under the wireless communication control of the control apparatus is transmitted, and each of the wireless communication apparatuses can grasp conditions of communication within the communication network.